Dear Friends of Maine Lakes, Thank you for visiting our Interactive Field Guide! Though the primary content pertaining to species identification in this Guide is—for the most part—still correct and useful, the site itself is no longer fully-functional (nor able to be updated). The entire Guide will soon be replaced by a new, expanded website-version of the Maine Field Guide to Aquatic Phenomena. So please stay tuned! Thank you for your patience!

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Milfoil comparison table
Milfoil comparison table

Myriophyllum sibiricum


Northern Milfoil colony
Northern water-milfoil in-situ

Description: Northern water-milfoil has two distinct leaf types: submersed leaves and emergent leaves associated with the flowers (called bracts). The submersed leaves are finely feather-divided (1 to 5 cm long), with 5 to 14 pairs of leaflet pairs per leaf. whorls of 4 or 5 leaves are spaced (up to 1 cm apart) along the stem. Northern milfoil produces flowers and fruits above or at the water's surface on erect (4 to 15 cm) spikes. The bracts have entire or slightly serrated margins. Even when fully developed, the flowers are very small. The bracts are the same length or slightly longer than the flowers and fruits. (A hand lens is helpful for studying the flowers and bracts.) Toward the end of the growing season, egg-shaped winter buds (or turions) comprised of small stiff leaves are formed along the submersed stems.

northern water-milfoil Range Map
U.S. range map of northern water-milfoil

U.S. Range: Northern water-milfoil is native to Maine, new England and to other parts of the United States.

Look Alikes: The native milfoil that northern water-milfoil most closely resembles is whorled water-milfoil. Northern milfoil may also be confused with two of the invasive milfoils: variable water-milfoil, and Eurasian water-milfoil. Northern watermilfoil is the closest native look alike to Eurasian water-milfoil and has been known to hybridize with this invader.

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Northern Water Milfoil flower Northern Water Milfoil in-situ Northern Water Milfoil specimen Northern Water Milfoil range map Northern Water Milfoil illustration Northern Water Milfoil flower illustration

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